The present invention relates generally to the field of air filtration and, more particularly, to a media holding module designed to hold various granular and palletized gas phase air filtration media.
Gas phase air filtration began in the 1960s as a way to chemically remove corrosive and/or odorous gases using a dry media. Prior to the development of potassium permanganate (KMnO4) on alumina, most air scrubbing was either via liquid scrubbing towers or activated carbon.
Once a suitable media was developed, such as potassium permanganate (KMnO4) on alumina, a means for supporting it in an air stream was needed. Media holding flat panels of various sizes and depths similar to those used for activated carbon initially were used. However, it ultimately was decided that a standardized size based on a convenient airflow could be the basis for sizing equipment. Standard sized media holding containers (or modules) therefore were created. The modules included perforations or openings in opposing walls through which air entered and exited. Such modules were formed of metal or plastic.
Despite advances in the analysis of airflow dynamics over the years, the design of media holding modules has changed little over time. A commonly used design consists of a flat box-like panel, much like the basic design of a traditional home HVAC filter. Perforations are formed in the large opposing walls of the module, and filtering media is poured into openings, filling the interior cavity of the module. The module then is installed into a module housing disposed in the interior of a duct so that the module occupies the entire cross-section of the duct, forcing the air to travel through the module and the filtration media contained therein. Another prior art module design uses a thin “V”-shaped chamber supported between rectangular side plates that is filled with media and similarly mounted within a duct.
However, all known prior art module designs suffer from the same shortcomings, and nobody, to applicant's knowledge, has sought to redesign the modules to overcome those shortcomings. For example, prior art modules suffer from inefficient airflow due to turbulence and resistance. Areas of dead flow media zones decrease air filtration efficiency. Poor sealing between the modules and the ducts allows air to bypass the filtration media. Pressure drops created by the design of prior art modules lead to poor media utilization. Additionally, prior art modules are not configured to maintain multiple discrete layers of filtration media as is desirable in modern filtration applications.
Accordingly, there exists a need for an improved media holding module design to overcome the limitations found in the prior art. Desirably, the media holding module is configured to hold several different media in series, in discrete and separate layers. More desirably, such a media holding module is configured with a contoured inlet that introduces air to the media earlier than in traditional prior art module designs, reduces dead flow media zones to increase media utilization and smoothes airflow to reduce drag, pressure drop and uneven airflow patterns. Most desirably, such a media holding module is configured such that its support members are outside of the airflow path.